This thesaurus covers the fields of information science and librarianship to a depth that will adequately support indexing, with coverage of related and peripheral fields as warranted by the strength of their relationship to information science and librarianship. Among the related fields are computer science, linguistics, and behavioral and cognitive sciences. More limited coverage of peripheral fields such as education, economics, management, statistics, and sociology is also included. The thesaurus contains 1,353 preferred terms (descriptors), 778 nonpreferred terms (Use references), and 36 broad terms used to group related concepts (facet indicators), as well as scope notes and definitions of ambiguous terms. This revision contains both a net increase of 103 descriptors and 35 changed terms from the first edition. The thesaurus includes a discussion of changes in the second edition; guidelines for use; a bibliography (15 titles); lists of terms added, deleted, and changed in the second edition; a facet list; alphabetical display; hierarchical display; and rotated display. (DLS)